Mattress for bed with step deck and bed therewith

ABSTRACT

A mattress comprises a resilient layer having a lower portion and side walls shaped to generally mate with a recessed bed deck and one or more cells supported in relation to the resilient layer and generally within the recess. The cells have a low air permeability envelope and an inflation structure within the envelope. The inflation structure is configured to expand within the envelope when unloaded to cause the envelope to fill with air.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of pending application Ser. No. 11/810,215, filed Jun. 5, 2007, which is a continuation-in-part of pending application Ser. No. 11/616,266, filed Dec. 26, 2006, which is a continuation of application Ser. No. 11/002,604, filed on Dec. 2, 2004, granted as U.S. Pat. No. 7,155,766 on Jan. 2, 2007, assigned to the assignee of this application, the disclosures of which are hereby incorporated by reference.

BACKGROUND OF INVENTION

This invention relates in general to beds and more particularly to beds having a step deck and mattresses for use on beds having a step deck.

Beds with step decks are well known. Such a bed is manufactured and sold under the name VERSACARE by Hill-Rom Company, Inc. of Batesville, Ind., USA.

SUMMARY OF INVENTION

The present invention is directed towards a mattress comprising a resilient layer having a lower portion and side walls shaped to generally mate with a recessed bed deck and one or more cells supported in relation to the resilient layer and generally within the recess. The cells have a low air permeability envelope and an inflation structure within the envelope. The inflation structure is configured to expand within the envelope when unloaded to cause the envelope to fill with air.

The invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a partially cutaway perspective view of an exemplary bed and mattress, shown in solid line in a conventional bed position and in phantom line in a seated position.

FIG. 2 is a perspective view of the bed shown in FIG. 1 with the mattress removed.

FIG. 3 is a partially cutaway perspective view of an exemplary mattress.

FIG. 4 is a sectional view of the mattress shown in FIG. 3.

FIG. 5 is a partially cutaway perspective view of an exemplary mattress with a topper.

FIG. 6 is a sectional view of the mattress and topper shown in FIG. 5.

FIG. 7 is a diagrammatic representation of a longitudinal section of the mattress shown in FIG. 3.

FIG. 8 is a diagrammatic representation of a longitudinal section of the mattress shown in FIG. 5.

FIG. 9 is a partially cutaway perspective view of an exemplary construction for representative cells of the mattress, wherein the cells have different amounts of foam filling.

FIG. 10 is a partially cutaway perspective view an exemplary construction of a single cell.

FIGS. 11A-11D are diagrammatic representations of the mattress at various stages of use.

FIG. 12 is a partially cutaway perspective view of an optionally powered mattress.

FIG. 13 is a partially cutaway perspective view of an exemplary construction for representative cells of the optionally powered mattress, wherein the cells have different amounts of foam filling.

FIG. 14 is a partially cutaway perspective view of an exemplary construction for representative cells of the optionally powered mattress, wherein one of the cells is inflated and another is deflated.

FIGS. 15A-15C are diagrammatic representations of side elevations of the optionally powered mattress, showing inner walls of alternating cells in three separate zones, wherein the inner walls are subject to alternating pressure inflation phases.

FIG. 16 is a graph of exemplary alternating cell pressures in head, seat and foot zones of the optionally powered mattresses.

FIG. 17 is a graph of exemplary cell pressures over time of the non-powered and optionally powered mattresses.

FIG. 18 is a graph of exemplary cell pressures during various modes of operation of the optionally powered mattress and a conventional alternating pressure mattress.

DETAILED DESCRIPTION

Referring now to the drawings, there is illustrated in FIG. 1 a partially cutaway perspective view of an exemplary bed 110 having a head end 112, a foot end 114, and right and left sides 116, 118. The bed 110 includes a bed frame 120 and a bed deck 122 supported by the bed frame 120. The bed 110 may include head and foot end side rails 124, 126 supported in relation to the bed deck 122. An exemplary mattress 10 is supported by the bed deck 122. The mattress 10 provides a user support surface 30 for supporting a person using the bed 110. The bed 110 may assume a variety of positions, such as a conventional bed position, as shown in solid line, and a seated position, as shown in phantom line. This may be achieved by articulating the bed deck 122.

The bed deck 122 may include a head section 132, a seat section 134, and a foot section 136, which may respectively include head, seat and foot pans 138, 140, 142, as shown in FIG. 2. When articulating the bed deck 122, the head and foot sections 132, 136 may move relative to one another or relative to the seat section 134. The head section 132 and the foot section 136 may move relative to each other to change the angle of inclination of the back and the legs of the person using the bed 110 with respect to the seat section 134. An example of an articulation of the bed deck and mechanisms that facilitate movement of the bed deck is described in U.S. Pat. No. 5,715,536, to Weismiller et al., issued Feb. 10, 1998, the disclosure of which is hereby incorporated by reference.

Additionally, the bed deck 122 may be in the form of a generally V-shaped step deck, including an upper deck 144 and a central, longitudinally extending recess 146, which may be defined by a lower deck 148 of the bed deck 122 and a side wall 150 at least partially surrounding the recess 146 and connecting the lower deck 148 to the upper deck 144. The upper deck 144 may include longitudinally extending-upper deck side portions 152 and a head end upper deck portion 154 appended to a head end of the head section 132. An example of a bed deck is described in U.S. Pat. No. 5,692,256, to Weismiller et al., granted Dec. 2, 1997, the disclosure of which is hereby incorporated by reference. The head end side rails 124 may be mounted to the head section 132 of the bed deck 122 and the foot end side rails 126 may be mounted to the bed frame 120 adjacent to the seat section 140 of the bed deck 122. The bed deck 122 may cooperate with side rails 124, 126 to maximize the height at which side rails 124, 126 may be mounted relative to the support surface 30. The tops of side rails 124, 126 may be higher when in the raised position for improved coverage and protection of the person on the support surface 30 and the bottoms may be higher when in the tucked position for improved access to the bed frame 120.

The head end side rails 124 may be mounted to move with the head section 132 as the head section 132 pivots relative to the bed frame 120 between a lowered position and a raised position. The foot end side rails 126 may be mounted to the bed frame 120 and may be fixed relative to the bed frame 120 and seat section 134 so as to remain in a fixed position when the head and foot sections 132, 136 of the bed deck 122 are articulated.

In FIG. 3, there is illustrated a partially cutaway top perspective view of the exemplary mattress, generally indicated at 10. The mattress 10 is a non-powered self-inflating mattress, which may be inflated without the aid of an external tool, such as an external air pump. The mattress 10 is capable of providing a surface pressure profile that simulates a low air loss mattress, which is generally a mattress having a surface that has laser holes, a vapor-permeable cover, and an air blower source to directly or indirectly dissipate heat and moisture from the user/mattress interface. The user floats on surface while air is circulated air across the user's skin to reduce moisture and help maintain a constant skin interface pressure. True air loss utilizes 100-150 liters of air per minute to maintain normal skin temperature and moisture levels, yet not dry out therapeutic dressings.

The mattress 10 may have a plurality of zones. The mattress 10 shown has three different zones, namely a head zone 12, a seat zone 14, and a foot zone 16. Each zone 12, 14, 16 may include one or more air cells 18, 20, 22. The cells 18, 20, 22 may be connected to other cells in the same zones 12, 14, 16 but are preferably not connected to cells in other zones. This may be accomplished via hoses or conduits and check valves, which allow one way air flow to permit air to enter but not exit the cells 18, 20, 22. The cells 18, 20, 22 may be supported by a resilient layer or surround 24. The surround 24 may be a generally V-shaped surround, with a lower portion and side walls, which are dimensioned and configured to generally mate with the step deck 122. Depending on the shape of the surround 24 and shape of the cells 18, 20, 22, a filler 26 may be provided between the surround 24 and the cells 18, 20, 22, such as along the sides of the surround 24, as shown. As shown in FIGS. 5 and 6, an optional topper 28 may be provided over the surround 24 and the cells 18, 20, 22. The surround 24, the filler 26, and the topper 28 may be formed from a resilient material that provides improved pressure relief and support to increase user comfort. The surround 24, the filler 26, and the topper 28 may be covered by an anti-bacterial, anti-fungal top cover 30 that may be formed from a material that is fluid, stain and odor resistant. The cover 30 may include one or more ties for holding the mattress 10 in a generally fixed position in relation to a bed deck 122.

As shown in FIGS. 7 and 8, the bed 110 may have a beam 156 that extends laterally across the head end 112 of the bed 110. A corresponding portion of the mattress 10 may extend along the beam 156. The corresponding portion may be dimensioned and configured to accommodate the beam 156. For example, the surround 24 may be dimensioned to accommodate the beam 156, as shown in the drawings. Moreover, cells, or other resilient material, such as foam, provided along the beam 156 may be dimensioned to accommodate the beam 156.

In FIG. 9, there is illustrated a partially cutaway perspective view of an exemplary construction for representative air cells 18, 20, 22. As shown in the drawings, the cells 18, 20, 22 may be in the form of tubular air cells. The cells 18, 20, 22 may be filled with different quantities of foam fill, which functions as an inflation structure. The foam fill may be in the form of low durometer foam. The foam may be very soft so that the foam does not provide principal support for the user. In this way, the user may be supported by the air in the cells 18, 20, 22 rather than by the foam. The foam may be sealed with urethane, polyurethane, or other suitable sealing material, including but not limited to, for example, nylon coated with polyurethane, vinyl or polyvinylchloride, or nylon coated with vinyl to form a low air permeability envelope about the foam, as will be more apparent in the description that follows. The foregoing materials may permit the cells to be made via radio frequency welding. Urethane is a suitable foam as it is flexible and compliant and resists perforation through inherent strength.

It should be appreciated that the cells 18, 20, 22 may be tuned, for example, by varying the amount of foam in the cells 18, 20, 22. By varying the amount of foam in the cells 18, 20, 22, differential volumes of air may be established in each of the zones 12, 14, 16. For example, the cells 20 in the seat zone 16 may have the least amount of foam, the cells 18 in the head zone 18 may have more foam than the cells 20 in the seat zone 16 (i.e., a medium amount of foam), and the cells 22 in the foot zone 16 may have the most foam. These cell configurations are represented in FIG. 9.

Tuning of the cells 18, 20, 22 may be done in any suitable manner. For example, measurements may be taken using a conventional low air loss mattress to determine the amount of air in corresponding head, seat and foot zones with an average user resting on the mattress. It may be found that the air cells in the seat zone, which supports the user's main torso, which makes up most of the user's total body mass, have the least volume of air. The head zone air cells may have a greater volume of air than the seat zone air cells because the head zone air cells support the user's upper torso, which is made up of the user's upper chest, shoulders, and head, which are lighter than the user's main torso. The air cells in the foot zone may have the greatest volume of air because the user's legs are lighter than the main and upper torsos and thus form the least amount of the user's total body mass.

The aforementioned measurements may be used to determine the amount of air needed in each cell 18, 20, 22 of the exemplary mattress 10 so as to simulate the feel of a conventional low air loss mattress. A corresponding relationship may be established between the amount of air needed in each cell 18, 20, 22 and the amount of foam in each cell 18, 20, 22. The foam in the cells 18, 20, 22 in each zone 12, 14, 16 may be varied in any suitable manner. For example, the cells 18, 20, 22 shown in FIG. 9 include foam inserts 34, 36, 38 that are similar in shape. The foam inserts 34, 36, 38 shown are generally cylindrical in shape with a portion removed to reduce the volume of the foam inserts 34, 36, 38, the volume of the removed portion being dependent on the cell zone 12, 14, 16. In FIG. 10, an exemplary construction of the foam insert 36 for the seat zone 14 is shown with such a portion (shown in hidden line) removed along the length of the insert 36. In accordance with this technique, the heights of the various cells 18, 20, 22 may be substantially unaffected, or affected only slightly, while achieving a reduced volume for each respective cell 18, 20, 22.

To aid in assembly of the mattress 10, the foam inserts 34, 36, 38 may be differentiated from one another, for example, by the absence or presence of one or more identifiers, such as the marking notches shown in the drawings. The absence or presence of identifiers may function as coding for the foam elements 34, 36, 38.

Referring back to FIG. 9, each foam insert 34, 36, 38 may be hollowed out to produce a hollow space 34 a, 36 a, 38 a with a thin portion 34 b, 36 b, 38 b above the hollow space 34 a, 36 a, 38 a to reduce the supportive effect of the foam insert 34, 36, 38 to the user. A slice 34 c, 36 c, 38 c may be provided in a lower portion of each foam insert 34, 36, 38 and the inserts 34, 36, 38 may be designed with an inner profile that aids in cutting foam from blocks of foam material during the formation of the foam inserts 34, 36, 38. A thick portion 34 d, 36 d, 38 d below the hollow space 34 a, 36 a, 38 a may be provided to reduce the risk that the thick portions 34 d, 36 d, 38 d will become dislocated at the slice 34 c, 36 c, 38 c. Such dislocation may reduce the outer perimeter dimension of the foam inserts 34, 36, 38, which may modify the volume of air drawn into the cells 18, 20, 22 by the foam inserts 34, 36, 38 during inflation of the cells 18, 20, 22.

As further shown in FIG. 9, the foam inserts 34, 36, 38 may be sealed with an outer wall 40, 42, 44, which may cover the foam inserts 34, 36, 38 so as to function like a low air permeability envelope. The walls 40, 42, 44 may be formed from a transparent, translucent or other suitable material that may aid in easily identifying the cell identifiers so that the foam inserts 34, 36, 38 can easily be differentiated from one another during assembly of the mattress 10 for positioning of the foam inserts 34, 36, 38 in the proper cells 18, 20, 22.

In FIG. 11A, there is shown a side elevational view of the mattress 10 for use in supporting a user. The cells 18, 20, 22 are disposed in three zones 12, 14, 16. With a 175 pound user, the head zone 12 may, for example, have a nominal pressure of 14 mBar, the seat zone 14 may have a nominal pressure of 20 mBar, and the foot zone 16 may have a nominal pressure of 5 mBar. These pressures may be controlled by the foam volume within the cells 18, 20, 22. The foam inserts 34, 36, 38 may be provided to inflate each cell 18, 20, 22 though the check valves 45. When the user lies on the mattress 10, the different volumes may be reflected by different pressure rises in the respective zones 12, 14, 16.

It should be appreciated that, as the mattress 10 supports a user over a period of time, air in the cells 18, 20, 22 may diffuse through the walls 40, 42, 44, causing the cells 18, 20, 22 to deflate, resulting in compression of the foam inserts 34, 36, 38 in the cells 18, 20, 22, as graphically depicted in FIG. 11B. When the user is removed from the mattress 10, as shown in FIG. 11C, the foam inserts 34, 36, 38 decompress or expand, thereby expanding the cells 18, 20, 22, as depicted in FIG. 11D. Expansion of the foam inserts 34, 36, 38 draws air through check valves 45 to inflate the cells 18, 20, 22 without the need of an external tool. It should be appreciated that the user need not be removed from the mattress entirely but instead may be removed from one or more cells, thus permitting the foam insert of the effected cell to decompress or expand, and thereby permit the effected cell to expand.

When in use, the inflated mattress 10 may exhibit slow leakage of air. The air loss may be caused by diffusion, pinhole leaks, leaks through valves and tubing or hose connections, and the like. The leakage may be compensated for by an automated refill function, such as via the foam fill or inflation structure described above, without requiring an external tool, such as a pump.

The automated refill function may be provided by the foam inserts 34, 36, 38. The foam inserts 34, 36, 38 may function as an internal rebound or inflation structure, which may cause inflation of the cells 18, 20, 22 by drawing air through the check valves 45 when the mattress 10 is not in use. The inserts 34, 36, 38 may be formed from any suitable memory material that provides sufficient resiliency to restore the cells 18, 20, 22 to their nominal shape.

The pressure in each cell 18, 20, 22 may increase to equal the pressure required to support the user. That is, the average pressure on the user may equal the weight of the user divided by the mattress surface area contacted. By controlling the initial volume of air within a cell 18, 20, 22 via the shape of the foam inserts 34, 36, 38, the compliance (e.g., softness, resiliency, give) of the cell 18, 20, 22 may be determined, and when the user lies on the mattress 10, the area contacted may be correspondingly determined, allowing the controlled distribution of pressure over the body of the user.

The major support properties of the cells 18, 20, 22 may be defined by the volume of air in the cells 18, 20, 22 and the cell walls 40, 42, 44. The cell walls 40, 42, 44 may be relatively flaccid when the mattress 10 is not in use. Although the cell wall 40, 42, 44 of each cell 18, 20, 22 shown is similar, regardless of the foam insert size and shape, under various conditions, different cell wall configurations may be employed.

Although the air inside the cells 18, 20, 22 may be the most significant factor in determining the support characteristics of the cells 18, 20, 22, the foam inserts 34, 36, 38 may make some contribution to the support characteristics and feel of the mattress 10. However, the inserts 34, 36, 38 may be principally provided to inflate the mattress 10. Since the foam inserts 34, 36, 38 expand the cells 18, 20, 22 when unloaded, it is possible to keep the pressure contribution of the foam inserts 34, 36, 38 to a low level.

Each cell 18, 20, 22 may be individually tuned to a particular air volume so that regional control over support provided by the mattress 10 can be achieved. The air cells 18, 20, 22 may be aligned transversely to the longitudinal axis of the mattress 10 and arranged in zones to provide regionally varying properties. By arranging the cells 18, 20, 22 transversely, various pressure zones may be defined along the length of the user's body. Although head, seat and foot zones are described, various numbers of zones and zone geographies may be provided.

The different zones may differ in the amount of foam in the cells, and generally the ratio of foam volume to void volume (e.g., void volume shown in broken line in FIG. 10) within the cells. Although the foam may generally make some contribution to the support surface characteristics, by controlling the mechanical characteristics and configuration of the foam, this contribution may be as desired, which may be as minimal as possible while assuring reliable inflation of the cells when the cells are unloaded.

It should be appreciated that cells 18, 20, 22 within each zone 12, 14, 16 may be linked to the other cells 18, 20, 22 in the same zone 12, 14, 16. This permits a plurality of cells within each zone to be controlled together by a single check valve 45.

The foregoing mattress configuration may function like a powered low air loss mattress, while permitting passive and automated inflation of the cells 18, 20, 22.

Now with reference to FIG. 12, there is illustrated a partially cutaway perspective view of an optionally powered mattress 46. The construction of this mattress 46 is similar to that of the non-powered mattress 10 described above but adds the capability of working in conjunction with an external tool, such as an air pump and controller that are capable of producing an alternating pressure.

Exemplary cells 48, 50, 52 of the optionally powered mattress 46 may have foam inserts 54, 56, 58, like the above-described inserts 34, 36, 38. As shown in FIGS. 13 and 14, inner walls 59, 60, 61 may be provided within the foam inserts 54, 56, 58. These inner walls 59, 60, 61 may function like low air permeability envelopes that permit the mattress 46 to be inflated and deflated like a conventional alternating pressure mattress. The inner walls 59, 60, 61 may be connected together in an alternating fashion along the longitudinal axis of the mattress 46, and may terminate in fittings that can be attached to an alternating pressure mattress pump controller, as shown in FIGS. 15A-15C. This may allow the mattress 46 to be used for application of alternating pressure therapy, if prescribed by a caregiver, without the need to exchange the mattress 46.

In FIG. 13, there is illustrated a partially cutaway perspective view of an exemplary construction of representative cells 48, 50, 52 of the optionally powered mattress 46, wherein the cells 48, 50, 52 have different hollow foam inserts 54, 56, 58 formed from different amounts of foam fill, each with an inner wall 59, 60, 61 for the alternating pressure functionality. The inner wall 59, 60, 61 and the outer wall 69, 70, 71 may be formed from any suitable material that is capable of functioning like a low air permeability envelope, like the outer walls 40, 42, 44 described above.

In FIG. 14, there is illustrated a partially cutaway perspective-view of an exemplary construction for representative cells of the optionally powered mattress 46, wherein one of the inner walls 60′ is inflated and another inner wall 60″ is deflated. As shown in the drawing, the inner walls 60′, 60″ are inside the foam inserts 56, which in turn are inside the outer walls 70. It should be appreciated that the inner walls 59, 60, 61 and outer walls 70 may respectively function as primary and secondary bladders (e.g., inner and outer low air permeability envelopes).

The inner walls 59, 60, 61 of alternating cells 48, 50, 52 in each zone 64, 66, 68 may be subject to alternating pressure inflation phases. As shown in FIGS. 15A-15C, the alternating cells 48, 50, 52 for each zone 64, 66, 68 may be provided with separate check valves. Multiple filtered check valves may be provided in a single molded housing. The check valves may let air enter the cells 48, 50, 52, but not exit the cells 48, 50, 52. At least one of the end-most cells 62, shown in FIG. 12, at the head end of the mattress 46 may not be subject to an alternating pressure inflation phase and thus may provided with its own check valve. Consequently, the exemplary mattress 46 may have seven check valves in all, two for the alternating pressure inflation phases for each of the three zones 64, 66, 68 and one for the end cell 62.

In accordance with this construction, when the mattress 46 is not used in powered mode, the inner cells 59, 60, 61 are deflated, as shown in FIG. 15A, and the mattress has substantially the same patient pressure profile as the non-powered mattress 10 described above. In FIG. 15B, the mattress 46 is connected to a controller pump, which produces alternating pressure inflation phases for each of the three zones 64, 66, 68. In this configuration, the mattress 46 is an alternating pressure mattress. In FIG. 15C, the mattress 46 is connected to the controller pump, which produces equal pressure in the cell 48, 50, 52 in each of the three zones 64, 66, 68. This configuration may be desirable for a user who does not desire the softer feel of a low air loss mattress or the alternating pressure of an alternating pressure mattress.

It should be appreciated that when the controller pump is not connected to the mattress 46, ports A, B are closed so that air is not permitted to enter the inner walls 59, 60, 61 through the ports A, B. Air within the inner walls 59, 60, 61 can be evacuated from the inner walls 59, 60, 61 through check valves.

In FIG. 16, there is a graph illustrating that the optionally powered mattress 46 has a performance characteristic similar to the non-powered mattress 10. The graph shows exemplary cell pressures for the non-powered mattress 10 and the optionally powered mattress 46 under various conditions. One curve in the graph represents pressure characteristics of the non-powered mattress 10 in each of its zones, wherein the cells in the zones are sealed apart from one another. In the powered mattress 46, alternating cells are in fluid communication with one another. The curves represent pressure characteristics of the optionally powered mattress 46 in each of its zones, wherein the inner walls 59, 60, 61 in the alternating cells are not evacuated. Consequently, the air in the inner walls 59, 60, 61 is distributed substantially equally throughout the alternating cells in the three zones 64, 66, 68, so a differential pressure in each of the zones 64, 66, 68 is not readily achieved. For the optionally powered mattress 46 to function like the non-powered mattress 10, the inner walls 59, 60, 61 should be evacuated.

It should be appreciated that there is a tendency that the air in the inner walls 59, 60, 61 will passively diffuse into the region of the cells 48, 50, 52 outside the inner walls 59, 60, 61 so that a differential pressure in each of the zones 64, 66, 68 will eventually be achieved. Achievement of this pressure differential can be accelerated by actively evacuating the air from the inner walls 59, 60, 61. This active evacuation can be done in various ways. For example, the air in the inner walls 59, 60, 61 can be evacuated through the check valves with a pump, by sitting on or otherwise applying a load to the inner walls 59, 60, 61 to compress the inner walls 59, 60, 61, or by rolling the mattress 46 up to compress the inner walls 59, 60, 61 and thus force air in the inner walls 59, 60, 61 out through the check valves. These checks valves may allow air to flow out of the inner walls 59, 60, 61 but not into the inner walls 59, 60, 61. Such check valves are schematically represented for illustrative purposes along hoses or conduits A and B in FIGS. 15A-15C. Through active evacuation, differential pressures in the three zones 64, 66, 68 can be achieved, as is characteristic of the three evacuated curves, which are similar in characteristic to the curve for the zones 12, 14, 16 in the non-powered mattress 10 with reference to FIG. 3.

In FIG. 17, there is illustrated a graph of exemplary cell pressures over time for the optionally powered mattress 46. The graph shows two curves, one curve representing a high cost, high output alternating pressure controller pump (i.e., 40 liters per minute) and another curve representing a low cost, low output alternating pressure controller pump (i.e., 10 liters per minute) connected to the mattress 46. The general pressures reached and maintained are similar with both pumps, demonstrating that the mattress 46 can be effectively used with a wide range of controller pumps.

In FIG. 18, there is illustrated a graph of exemplary cell pressure comparisons. The graph shows the alternating pressure cells (labeled “A Cells” and “B Cells” in the graph) of the optionally powered mattress 46 reaching substantially that same pressure over time. The cells are connected together alternately along the longitudinal axis of the optionally powered mattress 46 and are connected to a controller pump that inflates the A cells while deflating the B cells and then deflates the A cells while inflating the B cells. This may continue, for example, over cycles of about 5, 10 or 15 minutes. The graph also shows the performance of similar cells of the optionally powered mattress 46 and a conventional alternating pressure mattress. The graph illustrates that the optionally powered mattress 46 has performance characteristics similar to a more conventional powered alternating pressure mattress.

In use, the inner walls 59, 60, 61 within the foam inserts 54, 56, 58 of each cell 48, 50, 52 may provide an alternating pressure surface. The inner walls 59, 60, 61 may be actively controlled, for example, to provide a cyclic inflation and deflation. The optionally powered mattress 46 shown has two sets of inner walls 59, 60, 61 that may alternately inflate and deflate, sequenced such that cells 48, 50, 52 may be inflated before the adjacent cells are deflated, to insure that the user remains actively supported. This, in turn, may alter pressure distribution on the user over time, and therefore may improve circulation and reduce the incidence of decubitus ulcers and/or promote healing of such ulcers. The inner walls 59, 60, 61 are within the outer walls 69, 70, 71, and may be of much smaller volume. The pressure may be controlled by a standard alternating pressure controller pump as alternative therapy, when needed, without replacing the optionally powered mattress 46, which is otherwise passive, with another different active mattress/pump combination.

Like the non-powered mattress 10 described above, the optionally powered mattress 46, as shown in FIG. 12, may have a surround 76, a filler 77, and a topper 78 and be covered with a cover 79, which may function as an environmental barrier. Each air cell 48, 50, 52 may be connected via a hose to form plural zones, such as the head, seat, foot zones 64, 66, 68. The cells in each zone 64, 66, 68 may have a different volume of foam that translates into a different captured air volume upon inflation. This results in a different firmness for each zone 64, 66, 68 and is similar in feel to more costly therapy mattresses that incorporate active control over zone pressure.

The inner wall 59, 60, 61 may be formed integrally with the outer walls 69, 70, 71 of each cell 48, 50, 52. In this case, during manufacture, a polyurethane sheet may be radio frequency welded into two concentric spaces, with a respective port formed to communicate with each space. The foam inserts 54, 56, 58 may be inserted within an inner space in a hollow region between the inner wall 59, 60, 61 and the outer wall 69, 70, 71.

The present invention is also applicable to non-medical mattresses and other ergonomic support surfaces, such as beds, couches, chairs, loungers, and the like.

The invention has been explained and illustrated in an exemplary embodiment. However, it must be understood that the invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope. 

1. A mattress for a bed having a deck comprising a recess at least a portion of which is defined at least in part by a lower deck and one or more side walls, the mattress comprising: a resilient layer having a lower portion and side walls shaped to generally mate with the recess; and one or more cells supported in relation to the resilient layer and generally within the recess, the cells having a low air permeability envelope and an inflation structure within the envelope, the inflation structure being configured to expand within the envelope when unloaded to cause the envelope to fill with air.
 2. The mattress according to claim 1 further comprising a check valve serving to permit air flow into the envelope while preventing air flow from the envelope, the inflation structure being configured to expand within the envelope when unloaded to cause the envelope to fill with air through the check valve.
 3. The mattress according to claim 2, wherein the inflation structure comprises a foam that is sufficiently resilient to inflate the envelope through the check valve while providing a low contribution to the compliance of the cell.
 4. The mattress according to claim 1, wherein the cells comprise a plurality of cells in a plurality of zones, each zone comprising at least one of the plurality of cells, the cells of each of the zones differing from the cells of each of the other zones by an inflation volume defined by the configuration of the inflation structure.
 5. The mattress according to claim 4, wherein each zone has at least one check valve serving to permit air flow into the cells therein while preventing air flow from the cells therein.
 6. The mattress according to claim 4, wherein the plurality of zones comprises at least three separate pressure zones corresponding to a head, knee and foot section of the bed.
 7. The mattress according to claim 1, wherein the layer is a foam layer and the cell is one of a plurality of cells disposed within the high density foam layer.
 8. The mattress according to claim 1, further comprising a topper situated above the one or more cells.
 9. The mattress according to claim 1, further comprising a cover over the mattress, the cover being configured to provide an environmental barrier.
 10. The mattress according to claim 1, wherein the inflation structure comprises a foam structure having sufficient resiliency to return the cell to a nominal state after compression of the cell and thereby draw in air through a check valve to inflate the cell, the foam structure being a foam cylinder, the cell volume being controlled by removing a portion the foam cylinder along a length thereof.
 11. The mattress according to claim 1, further comprising a bladder within the inflation structure, the bladder having an external port for selective inflation and deflation of the bladder via an external tool.
 12. The mattress according to claim 11, wherein the inflation structure comprises a hollow foam insert, the bladder being inserted within a hollow space of the foam insert, the hollow space being principally disposed within an upper portion of the foam insert close to a user support surface of the mattress.
 13. The mattress according to claim 11, further comprising an alternating pressure controller, the alternating pressure controller being operable to sequentially inflate and deflate the bladder.
 14. The mattress according to claim 11, wherein the bladder is formed integrally with the envelope.
 15. The mattress according to claim 11, wherein the inflation structure comprises a cylindrical foam structure having a portion removed along a surface of the cylindrical foam structure, the bladder being within a D-shaped hollow space of the cylindrical foam structure in an upper portion of the cylindrical foam structure.
 16. The mattress according to claim 15, wherein the one or more cells are one of a plurality of cells in a plurality of zones comprising at least three zones comprising head, seat and foot zones each comprising at least one cell of the plurality of cells, the cells being cylindrical and transversely disposed along a length of the mattress, the cylindrical foam structure in the cells in each of the zones differing in cross section to provide differential support for the head, seat and foot zones, and two alternating pressure zones each comprising the bladders of alternating ones of the cells along the length of the mattress.
 17. A bed comprising: a bed frame; a bed deck supported in relation to the bed frame, the bed deck comprising a recess at least a portion of which is defined at least in part by a lower deck and one or more side walls; a mattress having at least a portion in the recess extending across the lower bed deck, the mattress comprising: a resilient layer shaped to generally mate with the recess; and a cell supported in relation to the recess, the cell having a low air permeability envelope and an inflation structure within the envelope, the inflation structure being configured to expand within the envelope when unloaded to cause the envelope to fill with air.
 18. The bed according to claim 17 wherein the bed deck further comprises an upper deck, the side wall being between the lower deck and the upper deck, the layer having a portion resting on the upper bed deck.
 19. The bed according to claim 17 wherein the bed deck is a generally V-shaped bed deck and the resilient layer is a generally V-shaped layer to generally mate with the V-shaped recess. 